1. Field of the Invention
The present invention relates to an adjustable wrench, and more particularly to an adjustable wrench that can hold a hexangular head of a bolt securely and can be operated with bolts of different sizes smoothly.
2. Description of Related Art
A conventional adjustable wrench as disclosed in U.S. Pat. No. 6,739,223 comprises a handle, a fixed jaw, a roller and a movable jaw. The fixed jaw is formed on an end of the handle and has a curved inner side. The roller is rotatably mounted in the curved inner side of the fixed jaw to rotate in an opposite direction relative to the handle. The movable jaw is slideably mounted on the end of the handle, faces the fixed jaw and the roller to hold and rotate a hexangular head of a bolt in a backward or a forward direction.
Although the conventional adjustable wrench can be used to rotate bolts of different sizes in the backward or the forward direction, the rotating direction of the roller is opposite to the rotating direction of the conventional adjustable wrench when the handle is rotated in a backward direction. Then, the conventional adjustable wrench cannot rotate backwardly with a smaller range of movement.
In addition, the movable jaw of the conventional adjustable wrench does not have a structure to block the hexangular head of the bolt. With reference to the FIG. 8 of the above-mentioned patent, when the conventional adjustable wrench is used to rotate a small-size bolt, the engaging position between the hexangular head of the small-size bolt and the jaws of the conventional adjustable wrench is deeper than the engaging position between the hexangular head of the ordinary-size bolt and the jaws of the conventional adjustable wrench. When the conventional adjustable wrench is rotated, the corners of the hexangular head of the small-size bolt may be worn and torn by the jaws of the conventional adjustable wrench. Furthermore, when the bolt is rotated with the jaws of the conventional adjustable wrench, the conventional adjustable wrench does not have a notch to yield the corners of an ordinary-size bolt and this will make the corners of the ordinary-size bolt broken.
To overcome the shortcomings, the present invention provides an adjustable wrench to mitigate or obviate the aforementioned problems.